The present invention relates to an image data processing apparatus for comparing image data having a plurality of pixels, and more particularly to an image data processing apparatus for comparing image data based on color feature information of the images. The present invention also relates to a computer program product for use in the image data processing apparatus.
Generally, image database stores and manages image data with attribute information such as creation dates, correction dates, file names, file formats etc. and search information such as keywords, shape features, colors, sound etc. added thereto.
In searching the image data in the image database, it is general to designate the search information such as the keyword etc. corresponding to the subject image. For this purpose, user need to add beforehand the search information indicative of image features to the image data. It is a burden to users. To lighten user""s burden, it is effective to automatically extract features from the images and add extracted features to the images. The features to be extracted from each image are, e.g., a texture periodicity of the image, a basic pattern constituting the texture of the image or a feature related to a color representing the image (referred to as xe2x80x9ca color featurexe2x80x9d hereinafter).
These automatic extraction and addition of image feature make it possible to search a similar image for an image of a search key with the image as the search key based on features extracted from the image, so that the processing efficiency for the search and search accuracy are improved.
As a way of automatically extracting the color feature as one feature information from the image, for instance, Japanese Patent Laid-Open Publication No. 5-274372 discloses a method which detects the amount of each color constituent included in the image. The detected information is coded and added to image data. How to carry out the search with the use of this information and how to compare images are not described. According to another method disclosed by Japanese Patent Laid-Open Publication No. 8-16789, colors of the image are divided to several groups, a frequency of pixels included in each group is counted, a ratio of the frequencies is set as a feature, and images are compared with the use of the ratio. However, no specific means is depicted and only a conceptual description is made. Thus none of the above prior arts reveals a concrete means for extracting the color feature as a feature from the image, thereby comparing and searching images based on the color feature.
Since color images are supposed to be employed more and more in consequence of enhanced performance of information processing apparatuses and advancement in digitization of information, it becomes greatly important to handle the color feature of the image. Accordingly, an apparatus for processing image data, more specifically, extracting color features from the image and comparing images based on the color feature is earnestly demanded.
The object of the present invention is therefore to provide an image data processing apparatus for extracting a feature information from images and comparing images based on the color feature information.
The another object of the present invention is to provide a computer product in a memory to achieve image data processing for extracting a feature information from images and comparing images based on the feature information.
In order to achieve the aforementioned objective, an image data processing apparatus for processing data of images each having a plurality of pixels is provided in a first aspect of the present invention, which comprises an extraction controller whereby colors constituting the image data are sorted to a plurality of color groups based on predetermined color elements, a count of pixels belonging to each color group is counted, so that feature information of images is extracted, and a comparison controller whereby a plurality of images are compared based on the feature information extracted by the extraction controller.
In an image data processing apparatus provided according to a second aspect of the present invention, the apparatus includes an input controller through which image data of a plurality of images are input, an extraction controller which classifies colors constituting the image data to a plurality of color groups based on predetermined color elements, counts pixels belonging to each color group for every image input through the input controller, thereby extracting feature information of each image, an image database for storing image data input through the input controller such that the image data are linked to the feature information extracted by the extraction controller, a designating device for designating a search key image as a search key, and a search controller which compares the feature information of the search key image designated by the designating device with the feature information of each image stored in the image database, and searches for image data having feature information similar to that of the search key image.
According to a third aspect of the present invention, a computer program product in a memory is provided to process data of images each consisting of a plurality of pixels. The computer program product includes an extraction control whereby colors are divided to a plurality of color groups based on predetermined color elements, pixels belonging to each color group are counted, so that feature information of images is extracted, and a comparison control whereby a plurality of images are compared based on the feature information extracted by the extraction controller.
The computer program product further includes a registration control whereby the feature information extracted by the extraction control and the image data are registered in the image database such that they are linked, and a search control whereby image data are searched from the image database with the use of the comparison control.